Some needle safety mechanisms use a trigger or other structure that actuates a spring to retract the needle into the barrel or to urge a cover over the needle. Such retraction and extending cover systems have significant limitations, including inadvertent exposure to blood by the user from blood spray or blood “back-splash” during the deployment process. Furthermore, contact of the needle safety mechanism with the needle during deployment, for example, covers with guide holes riding the needle shank, may cause significant blood-born exposures by spraying. Another limitation is that the trigger is often not adequately protected from inadvertent actuation. Inadvertent actuation may result in needle safety mechanism deployment before administration is complete, which can render the syringe un-usable and/or waste expensive medication.
Consequently, there is a need for a needle safety mechanism that protects users from both needlesticks and contact with blood, and improves the simplicity and dependability of the deployment process for users.